Dystonia has been defined as a syndrome of sustained muscle contractions, frequently causing twisting and repetitive movements, or abnormal postures. Recently, a mutation in the gene THAP1 was identified as the cause of DTY6 dystonia in Amish-Mennonites. Follow-up high-throughput screening of patients with sporadic and familial, mainly adult-onset, primary dystonia showed that a diverse assortment of THAP1 sequence variants is associated with varied anatomical patterns and onset ages of primary dystonia in diverse populations. Clearly, THAP1 appears to be the most important genetic etiology for adult-onset primary dystonia identified to date. THAP1 encodes the transcription factor THAP1. Using a large biorepository containing DNA and lymphocytes from subjects with adult-onset primary dystonia, we will examine associations between dystonia risk and recently identified THAP1 sequence variants, and interrogate THAP1 for copy number and additional coding and non-coding sequence variants. Using lymphoblastoid cell lines, transfected cell lines and gene expression profiling, we will determine the effects of individual THAP1 sequence variants on THAP1 expression and function. This work will have immediate clinical ramifications in the context of genetic testing and counseling. Recent studies in humans and animal models strongly suggest that DYT1, DYT6 and other forms of dystonia may be neurodevelopmental disorders. Transcriptional dysregulation and abnormal cerebellar output have been other major themes in dystonia research. Accordingly, we will examine the developmental expression of THAP1 protein and transcript in neural tissues and generate a model of DYT6 dystonia by knocking-out the Thap1 gene in mice. Preliminary data indicates that THAP1 is expressed at high levels in developing Purkinje cells. Morphological studies in Thap1-KO mice will allow us to test the hypothesis that THAP1 is essential for the normal morphological development of cerebellar Purkinje cells. In addition, data from ChIP-Seq and ChIP-chip experiments will be merged in order to identify THAP1 DNA binding sites in vivo during the maturation of cerebellar cortex. Completion of these experiments will unveil dystonia-associated cellular networks, point out candidate genes for primary dystonia and define molecular targets for the treatment of dystonia. PUBLIC HEALTH RELEVANCE: Dystonia is a common disorder of the nervous system that manifests as prolonged muscle contractions leading to abnormal postures of the face, neck, trunk and limbs. Mutations in the THAP1 gene cause dystonia in children and adults. Our research will attempt to determine exactly how THAP1 mutations lead to the development of dystonia.